Cementitious composition



July 22,l 1952 /MMERs/o/v TESTS o/v 2x2"6YPsu/u c0555 w. c. RIDDELI. ETAL 2,604,411

CEMENTITIOUS COMPOSITION Filed July l0, 1950 c 5 LL/vEw /v H6 ESDUL U 45 TIME 0F MMERS/O/V /N HOURS AT 70 F GEUGE B. Kl BY Patented July 22,'1952 v cEMEN'rI'rIOUs COMPOSITION Wallaee o. Riddell, Berkeley, andGeorge B. Kirk, Redwood City, Calif., assignors to Henry J. KaiserCompany, a corporation /oir Nevada l Application July 10, 1950, SerialNo. 172,867 n This invention relates to the preparation ofWater-resistant, or water-repellant, cementitious produ-cts; and,especially,A it relates to the production of water-resistant gypsumcompositions, such as gypsum wallboard, gypsum tile and other gypsumproducts.A y A Earlier Workers in this` field have developed or proposedmany methods for increasing. the water-resistance or water-repellency ofgypsum products, especially Wallboard, which, for example, would enableuse of thelatter as sheathing material in the construction industry.Included in such methods have been processes 'wherein matrialsimpartingl water-resistance or water-repellency werel'incorporated`in'the gypsum slurry -during the process rof.manufactura as well ascoating of the finished product with a waterproofing material. AThedisadvantage of the latter method is thatany break in the surface willpermit water penetration and absorption. The incorporation ofwater-repellency agents within the slurry isY an advance in, this art,but the processes heretofore employed have been rather expensive and,especially, haverequired expensive additives, and havev sometimesnecessitated either melting the agent or drying the treated slurry at anelevated temperature in order to eiect proper diffusion of the treatingagent and effective protection of the gypsum. 1

. According, to the present invention it has now been .found that thedisadvantages of earlier methodsare overcome and a water-resistantgypsum product is obtained by incorporating in the gypsum materialresidual fuel oil or pine tar or coal tar and a water emulsion of apetroleum wax, prior to drying." From about 0.5% Ito about l2.0% of wax,calculated on the dry basis, is added, in the form of an emulsion inwater. From 2.0% to 10.0% ofthe oil or taris added, and preferably from5.0% to 10.0% thereof. -'lheserpercentages arebased on theV dry weightvof the total -unset gypsum composition; and the percentage of waxrelates to the dry'substance.A -Higher amounts ycankbe added' but tendto-increase' the cost ofthe v24 claims. (ol. 10s-116) white to darkbrown and black.Y The melting points thereof vary also and may be ashigh as 200 F. These waxes are distinguished from paraffin, and other,waxes by their ycrystalline characteristics and chemical structure. Themicro waxes are not truly amorphous but tend toward illformed crystalsand approach the amor- Dhous state much more closely than do parainwaxes. Whereas the paraflin waxes are generally believed to be straightchain hydrocarbons having, on the average, a 24 to 26 carbon v-atomchain, the micro waxes appear rather to be mainly high molecular Weightbranched chain hydrocarbons; and the micro waxes havemuch'higher meltingpoints, which is Vconsistentwith this structure. The average particlesize of the micro wax is not over about one. micron diameter.A The microwaxes tend also to be resinous and sticky. The waxes are employed asaqueous emulsions which are available commercially. When the slack waxemulsion is employed, it is preferably added in an amount of from about1.0% to 2.0% wax, on the dry basis; and where micro wax emulsionisemployed, it is preferably. added in lan amount of from about 0.5% to1.0% wax, on the dry basis.

The term residual fuel oil as employed in this specification and claimsmeans the heavier residual fractions of petroleum', such as Bunker COil, heavy fuel oil and equivalent heavy petroleum fractions; but itexcludes thelighter fractions including gasoline, kerosene and dieseloils, onthe one hand, and the solid residues of processing, includingwaxes and asphalt, on the other hand. One sort of residual fuel oilvemployed herein is a petroleum fraction which has a. specific gravityof from 7.4 to 8.8, A. P. I. at 60. F.; and a flash point (closed cup)of from 205 F. to 212 F. It contains, upon analysisapproximately carbonand 10% hydrogen, the remainder being Ywater, sulfur, nitrogen,ash,'etc. In placeof, or in addition to, the residual fuel Oil there canbe employed also coal tar orv pine tar.. The .total amount `added ofresidual fuel oil, coal tar or pineV tar,r or any mixture Of thesecomponents, is preferably from 5.0% to 10.0%, based on the total dryWeight of the unset gypsumv composition; Mixtures of residual fuel oil,.coal tar and pine tar, or of any two of these materials, can beemployed.

It is an advantage of this invention that a gypsum board, suchl assheathing, or other gypsum product, so preparedis highly resistant tothe action of water. It is a-furtherjadvantage that the gypsum boardorother product canvvbe dried at atmospheric temperatures and, that'thestep of drying at elevated'temperaturs canl be Vavoidbut the presentinvention avoids the necessity forYV fusing the Waterproofing agent, orVany component thereof. Whatever may be the trueV mecha'- nism of thisaction, the eifect is that the small amounts of the wax and the oil ortar employed according to the invention enable production of Y Yexcellent Water-repellency in the gypsum products concerned, and withoutthe aid of heat in drying. e

It is a particular advantage of the present invention that vit enablesthe employment of a liquid :agent which does not volatilize off inprocessing, andV which does not require comminution or fusion. The Aoilortar, as deonedrbeing in the liquid state, is easily handled or pouredand blends readily with the gypsum material at anystage ofi the process.For instance, it can be added to*v thegypsumprior to calcining, and willnot volatilize oli" during that process; or it 'can be readily mixedinto the slurry. The liquid agent co-'acts with the Wax insome mane nerto render; the lnal gypsum productl quite Water-resistant, although', asshown in the annexed drawing, the Waxalone, or the oil alone isquiteineff'ectiva'as will be further described belovv.r ,o 'Y v I The Waxlemployedk and vresidual fuel oil, coal tar or pine tar canbe admixedwith the gypsum .mass in various Ways. The gypsum and the oil or tarcan, if desired, be admixed and then the mixture subjected tocalcination, for example, by heating vto about 170 C. (or 340 F.)Alternatively, the oil can be'mixed with the dry cal- 'cined gypsumy vbygrinding these components together, or by mixing in a screWrconveyor orother suitable mixing device; or the oil .can be mixed With the slurryVof calcined gypsum. The vvax emulsion can be v'mixed with thejd'ryvcalcined gypsum, or Withfthe slurry of calcined gypsum, by any suitablemeans. The emulsion eanalternatively be mixed With the Water vto beemployed in forming the gypsum slurry, and the Whole liquid then mixedwith the calcined gypsum to form Vthe slurry. In still another method ofmixing, ther wax emulsion and oil can beV first mixed together and thismixture added to VVthe VWater for slurrying, or to the calcined gypsumslurry andv the Whole thoroughly mixed.

VVThe admixture is,` suitably, cast orv otherwise `formed-into shape,and dried.

The attached drawing shows the advantageous results obtainedbythepresent invention, and in thisy iigure :the changes in Water-absorptionwith respect vto time of immersion in Water, for testlsamples of gypsum,as will be described, are

shown graphically.- These values were obtained by tests carriedV outinthe following manner. To four portions ofa calcined gypsum slurry areadded the agents shown in the/amounts stated: (l) no added agent; (2)10% residual fuel oil, Ybased on the dry Weight of `calcined gypsum;(-3) 2%'of a 50% emulsion of microcrystalline yWax in Water, the addedamount 'being calculated -onthe amount of dry wax With respectl to thedry Weight of calcinedjgypsum; (4i)V 10% residual Afuel oil and 2% of a50% 'emulsion of microcrystalline Wax in water, and in this test the oiland emulsion are each added directly to the gypsum slurry and thoroughlyadmixed. Twoinch cubes are cast from these slurries and are dried. Theyare then tested for Water absorption by immersing in Water of such depththat a one-inch head is maintained `above the pieces, at a temperatureof 70' F;, for times as shown on the graph. At the end of the respectiveperiods of immersion, test cubes are examined to determine the amount ofWater absorbed, and these'values, up to 72 hours, are plotted to givethe curves shown in the figure. The untreated gypsum (graph 1) absorbswater very rapidly. The gypsum treated With the oil alone (graph 2) andthat treated with microcrystalline Y Wax alone (graph 3) also absorbwater quite rapidly, although somewhat less rapidly than the untreatedmaterial. However, when both the oil Vand Wax emulsion are added thedecrease in water absorption (graph '4) is very pronounced and,satisfactory, and is more than Would be expected .from the resultsobtained 'with either agent alone. Y

vvThe petroleum Wax-water emulsions useful in this invention arecommercially available v'and comprise up to over 50% of the Waxemulsiiled in Water, a small amo-unt (up to about 3.5%), of anemulsifying agent preferably being employed to effect emulsiication.YThe emulsifying agent employed can be a protein, suchas casein. orsulfonated oil, sulfonated ori sulfated alcohol or carboxylicacid,starch,V clay, gums, or 'other desired agent. Varying amountsof wax canbe present in theemulsions available but for eco, nomic reasons as highan"V amount of Wax'as possible is desirable; but commerciallyavailableemulsions containing about 50% of Wax are useful. vllt, is lan advantagethat, by employing an emulsion of theY wax inv Water, rapid and thoroughdispersion in the calcined gypsum slurry is easily effected; and afurther advantage is that there is no problem of driving off orrecovering a solvent for the wax. o

Itis an advantage of' the present invention that the Watererep'ellencyadditives 'are effective Without the necessity for drying the gypsumprod-.- ucts at higher temperatures. This enablesxproi ductionofWater-repellent blocks 'ofn gypsum, or of structural elements, suchoasroofs or floors, vvhich are castand dried' at the site of use, undercircumstances Wheregthe employment of elevated drying temperature/S'islnot economically possible. y Y

The examples given below Will more clearly illustrate the mode oi?`carryingbut the invention.

Y Example I;

' Toa plastic gypsum vslurry inv/rater, contain-- ing '1000 grainsofcal'cined gypsum, are added 5% of residual fuel oil (Bunker C) and '1%of microcrystalline yax. (These percentages are based on thedry Weightoflthe ealcined gypsum and the amount of Wax refers to the amount of drywax.) The wax is added inthe form of an emulsion in Water. The whole isthoroughly Vad- -ni'ixed and then cast 'inteV '2" 4' cylinders, andrthewcylinders are dried fat; room temperature. By the immersion testdescribed above. there is a gain Vin Weight, or moisture absorption, vof2.7% after 30 minutes. In a test' carried out in exactly thesame wayexcept that 10% of the 'oil 'isfadded, there is a gain in `,Weig htiof2. 6% after -3 hours immersion. In skt-ill anotlrerjseries of ltestslcarriec'l out in the same way vexcept that there are ladded 0.5%. ofthemicrocrystalline wax (as above, in the form `of thewater emulsion) andof the oil; and in this series the test cubes show a water absorption of2.3% after 3 hours immersion. In contrast thereto, control test cubescontaining no additives show a water absorption of about 40% after 30minutes immersion and about 45% after 3 hours immersion.

Example II With a calcined 'gypsum slurry is thoroughly admixed 1% ofmicrocrystalline wax. based on the weightof dry solids in the slurry,thewax being added in the form of a 50% emulsion thereof in water, andthere is also added, with thorough mixing, 10% of residual fuel oil. Theslurry is formed into sheathing board and most of the production isdried at elevated temperature. The dryer air temperatures may exceed 350F., however, the core temperatures probably do not exceed 230 F. Severalof these boardsare removed from the production line before entering thedrier, and are dried in air and at room temperature (60 F. to 70 F.) andare then subjected to the immersion test. 2 x 4" sections with all edgesfreshly cut show a water absorption of only 2.7% after 30 minutesimmersion. Immersion tests, as described above, carried out upon 1/2" x12" x 16" sections with all edges freshly cut show a water absorption ofonly 3.8% after 5 hours immersion; 12" x 12" sections cut in the samemanner show 3.5% absorption after 5'hoursimmersion; and 6" x 6" sectionsabsorbed only 2.8% -water after 30 minutes absorption. Incontrastthereto, in testing gypsum sheathing board made in the samemanner but without water-repellent additives, 1/2" x 12" x 16" testpieces show a Water absorption of 52% after 5 hours immersion.

Example III To a plastic slurry of calcined gypsum is added, withintimate mixing, 1% microcrystalline wax, in the manner described inExample I, and 10% coal tar is also added with thorough mixing. Theslurry is cast in two-inch cubes and the cubes are dried at roomtemperature and subjected to the immersion test, exhibiting a gain inweight of l only 3.4% after 30 minutes immersion. Other cubes are madeof another sample of this same gypsum slurry, and in the same manner,except that 10% of pine tar is admixed instead of the 10% of coal tar.After similar drying these cubes are subjected to the immersion test andexhibit a gain in weight of only 3.5% after one hours immersion. y I

The microcrystalline wax employed in Examples I, II, and III, is in theform of an emulsion in water, containing by Weight of solids and 2% to3%, by weight, casein as empulsier; the emulsion having a specificgravity of 8 pounds per gallon. a pH of from 6 to 7, and a wax particlesize of from.0.5 to 1.5 microns diameter.

In preparing gypsum products according to this invention it is believedthat the microcrystalline waxes act, with the residual fuel oil or thetars disclosed, to produce the excellent water-repellent characteristicsby reason of the extremely line particle size of these waves and thethorough dispersion over the gypsum surfaces which vis attainablethereby. The micro wax may, so to speak,

occlude the oil or the coal tar or pine tar.. with the result that theliquid agent clings more firmly to the surfaces of the gypsum materialand is ybetter distributed thereover. High melting point melting pointslof about 196 F., as well as those having a lower melting point. forexample, vfrom abouti-,122 to about 165 F., are useful in invention. I y

a Example IV With a plastic slurry of calcined gypsum are thoroughlyadmixed, in the primary mixer, 1% of slack Wax having a melting point ofF., inthe form of'a 50% `emulsion in Water, emulsie'd with about 3.5%lgum emulsifier, and 6%k of Bunker C oil. The slurry is formed intosheathing board in thev usual manner, the board having gypsum corematerial disposed within fibrous liners; and the boards are dried atelevated temperature. The immersion test, as previously described, runon 1/2" x 6" x 6" sample sections, showed 9.1% Water absorption after 30minutes" immersion. In still another test, gypsum board is made in this'same manner but with the addition of 2% ofthe slack Wax (in emulsion)and 10% of the oil, and is then dried at room temperature :(60-70v F.)and the water absorption after, 30 minutes immersion is only 2.4%. l dIn a variation`,"aportion of the petroleum wax can be substituted for.or replaced by, rosin in the form of awater emulsion, such as isdisclosed and claimed inthe process set forth in our copendingapplicatiom Ser. No. 172,868, led July 10, 1950. That is to say, kwithan amount of the petroleum wax emulsion of the present invention thereis also admixed withthe gypsum material,

in the same mannergavrosin emulsion. TheV total amount ofvsolidadditives employed is from 0.5% to 2.0% by Weight,jon the dry basis.Where a preponderant amount of rosin is employed, residual fuel oil isemployed. It is particularly advantageous to employ a solidwater-repellency agentor constituent comprising rosin andmicrocrystalline wax, these components being added in the form of waterfemulsions, or as a single water' emulsion.

In this specification` and claims. percentages shown are by Weight,unless otherwise indicated. In general it is advantageous to employhigher percentages of the oil or tar describedwhen the lower amounts ofa wax, within the preferred range A, fory the wax, is employed. Whilethe employment of higher drying temperatures is advantageous for thepurpose of accelerating the drying o f the gypsum products,- suchtemperaturesjA are not vrequired in order to obtain thewater-'repellent' effect of the compounds employed herein; and .wherespeed of drying is not desired, or is not practicable, drying at air orroom temperature is useful. It is to be understoodthat'th usualmodifying additives can be, and are,adm1x ed inthe calcined gypsumslurries Where desired, as in making wallboard, for example. Y l Y Theabove examples and specific description have'been given for purposes ofillustration only and itis to `be understood that modiications andvariations can be made therein without departingfrom the spirit andscopeof the appended claims,

Having now described the invention what is claimed is:` V

1j. In' a process for producing a water repellant gypsum product thestep which comprises intimately admixing a water slurry ofcalcinedgypsum, from 0.5% to 2.0 based on the dry weight,

-of petroleum wax in the form of a Water emulsion, and from 2% to 10%.based on the dry weight, of at least one substance chosen from the 7group consisting of' resldual'fueloil; pine tar and coal-tan.' Y i" 2.Process'as in. claim 1 wherein the petroleum Wax is slack Wax and is inthe form of a Water emulsion containing a small amount of gumV emulsier.

. 3. Process as in claim 1 wherein the. petroleum wax ismicrocrystallnev wax.

4. Process as in claim 1 wherein a portion of said petroleum' waxemulsion is replaced by rosin emulsion.' `v Y f s 5. Process. for`producing a Water repellent gypsumproduct which comprises intimatelyadmixing. a' waterslurry of calcined gypsum,

V`frorn 0.5% to 2.0%, based on the. dry Weight,v of

petroleum wax infthe form of Water emulsion and from 5.0 %.'to 1.010%',bas"ed"on theV dry Weight. of at' least one substancelchosen from thegroup consistingof residual fuel oil,v pinev tar and coal tar, formingintor shape,v and-drying at room temperatur'e. f

y 6l 'Processjf preparingawater repellent gypsinn product'Whichfcoinprises'intimately admiX` ing .a calcined'gypsum slurry',from, 0.5% to' 110%,

based on'the'dry Weightfof.microcrystalline Waxin the 'form ofgalyateremulsion, and from 5% to 10%1 of at 'least'one substance chosen from thegroup consisting of residual'fuel.I oil, coal tar and pine tar,"ca sting lsaid admixture into shape, and

f group consisting oi'r'esidual' fuel' oil,V coal tar and pin'e'tar;`castingy boards,"of,V said admixture. and dryingjsaid ,b'oardQ l 11'.'Process". forV producing a water repellent gypsuinlproductf'whichcomprises intimately admixi-ng ."jgypsum 4 and at least one substanceclioseifromthe group consistingvof resdual'fuel oil; c'oaljtar andpinetar, cal'cning, said admix'-Y ture-fournira alyaterslurry thereof,intimately adiniinng' with said jwater slurry from 015% to 2.0%, basedvon thefdr'yjweight', of 'al petroleum Wax'in theforrn-of aA wateremulsion, andzdrying said admixtur'e, said substance chosen from'jthegroupconsis'ti-ngof Yr-sidual fuel oil, coal `tar and pine tar beingadded in anarnount of from 2% to 10% based on the totaldry weight.

12. Process for producing a water-rep'ellentl gypsum product-Whichcomprises intimately ad;-

mixing-aircalciried gypsum -slurryyfrom 0.5% to 2%,- fbasedsorrthecdryWeight*y of a solid Waterrepellency agentcomprisingvm-icrocrystalli-neWait androsin, inthe'formloflwateremulsionsrthereof, and from 5% to 10% of residual fuel oil, forminganddrying/lu l 13. A Water-repellent gypsum productV comprisingfasetmass` ofgypsum crystals protective- 8 lycoat'ed byfrorr1.:.0i5,%Iftoj'21.0%y of uniformly dispersed petroleum' .waxand'from 2% to A10 of at:l least one substance-chosen from the groupconsisting of: residualfuel oil, ,coal tar and; pine tali. '.Lg.. .1

14. A ,water-repellent' gypsum product cornprising a. set' mass .ofgypsum crystals protectively coated byfrom 0.5% `to 1.0% of'uniformlydispersed rnicrocrystallir1eA wax and from 5% to 10% of at least onesubstance chosen from the groupV consisting/of residual fuel oil,' coaltar and pinetar. Y- l I. s

15.l Product-fas in claim. 14 having dispersed therein from 5% to 10%'by Weight of residual fueloi-l. f -i L f Y 16. VProduct-'as in. claim'14 hating dispersed therein fromf5% tol 10%Y -by Weight of pine tar;

"17. `Product as in claim lehavin'g dispersed therein from 5% to 10% byWeight of coal tar.

18. A LWateri-r'epellent gypsum product cornprisingfa setriia'ss ofgypsum crystals protectively coated-.by from1% to 2% ofuni-for1nly dis.pers'ed slackwax and from 5% to 10% of at least one substance chosenfrom the group consisting of residual fueloiL' coal tar and pine tar.

19. 'Product as in claim 18 having dispersed therein from 5%to 10% byweight of residual fueloil.Y Y v 20. Product asl claimY 18 havingdispersed therein from 5% Vt `i"10% by u'feight.V of pine tar.

2li Product'as 'inclaim .1e/having dispersed therein from 5%{to 10%byfweight of coal tar'.

22; Water-repellentgypsum' board wherein 'the gypsumcore materialvcomprises a set mass of gypsumfcrystals protectively coated with from0.5% to' 1.0% vby Weight of uniformly dispersed microcrystallin'e Waxand with from 5% tov 10% by Weight of `at leasti one substance chosenfrom the group consisting of residual fuel oil, coal tar and pine tar.y'

23'. Water-repellent gypsum product comprising ya set mass off gypsumcrystalsfprotectively coated with'- from 0.5% to 2.0%of uniformlydispersed solid water-repellency agent comprising resin andmicrocrystalline Wax and vwith from 2% to 10% of `residual fuel oil.

' '24. In the process of producing a waterv-repellent gypsum-product,the step which comprises preparing a Water' slurrycontaining calcinedgypsum. from 2% to 10%,` based on the total dry Weight; of' at leaston'egsubstance chosen from the group. consisting of residual fuel oil,coal tarandpinetar', 'and `from 07.5% to 2.0%, based on the total dryweight, of petroleum wax in the 1 form of a water emulsion.

WALLACE'C; RIDDELL. v 's GsoRGneKiRK.

n asssasricssclrsn {'Tliej,following` references are of record in the'lepffthisgpat'entj l *A I K Y runnen STATES rAIENTs Numberf' 'i Name,Date 1,287,453 'Sanderson sDec 10, 1918 2,432,953. Camp Dec. 16, 19472.460,26? *Haddon AFelcVLjlQlQA 2,526,537 Camp Oct. 17, 1950 2,526,538s, .Camp ufr- Oct, 17,Y 1,950

1. IN A PROCESS FOR PRODUCING A WATER REPELLANT GYPSUM PRODUCT THE STEPWHICH COMPRISES INTIMATELY ADMIXING A WATER SLURRY OF CALCINED GYPSUM,FROM 0.5% TO 2.0%, BASED ON THE DRY WEIGHT, OF PETROLEUM WAX IN THE FORMOF WATER EMULSION, AND FROM 2% TO 10%, BASED ON THE DRY WEIGHT, OF ATLEAST ONE SUBSTANCE CHOSEN FROM THE GROUP CONSISTING OF RESIDUAL FUELOIL, PINE TAR AND COAL TAR.